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United States Patent |
5,245,592
|
Kuemmel
,   et al.
|
September 14, 1993
|
Wearing time measuring device for a removable medical apparatus
Abstract
A medical apparatus to be worn in the mouth comprises a battery-fed
measuring unit (15) including a clock generator (18) and a counter (20)
for counting the pulses of the clock generator. Accuracy of the time
measurement decisively depends on the precision of the oscillating
frequency of the clock generator. In the invention, there is used a clock
generator (18) wherein frequency precision is low. When the counted value
of the counter (20) is read into an external evaluating unit, the
measuring unit supplies a reference time required by the clock generator
(18) for generating a number of pulses. The evaluating unit calculates the
time corresponding to the counted value under consideration of the length
of the reference time. Thus, the evaluating unit measures the cycle length
of the pulses of the clock generator, and this cycle length is multiplied
by the number of the counted clock pulses. In this manner, time
measurement is performed in a precise manner without requiring a highly
precise clock generator.
Inventors:
|
Kuemmel; Dietmar (Aalen, DE);
Knoerzer; Gerhard (Aalen, DE);
Wurst; Juergen (Mutlangen, DE)
|
Assignee:
|
Frohn; Hermann-Josef (Linz, DE)
|
Appl. No.:
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820863 |
Filed:
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February 21, 1992 |
PCT Filed:
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July 13, 1990
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PCT NO:
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PCT/EP90/01150
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371 Date:
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February 21, 1992
|
102(e) Date:
|
February 21, 1992
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PCT PUB.NO.:
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WO91/01535 |
PCT PUB. Date:
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February 7, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
368/107; 368/10; 368/90; 368/202; 433/5; 433/6 |
Intern'l Class: |
G04F 007/00 |
Field of Search: |
368/10,90-95,200-204
433/5,6
|
References Cited
U.S. Patent Documents
3885310 | May., 1975 | Northcutt | 32/14.
|
4255138 | Mar., 1981 | Frohn | 433/6.
|
4629424 | Dec., 1986 | Lauks et al. | 433/6.
|
4764111 | Aug., 1988 | Knierim | 433/5.
|
Primary Examiner: Roskoski; Bernard
Attorney, Agent or Firm: Spensley Horn Jubas & Lubitz
Claims
We claim:
1. A wearing time measuring device for measuring the length of time that a
removable medical apparatus is worn, the device comprising:
a measuring unit, the measuring unit comprising a clock generator for
generating clock pulses, a counter for counting the clock pulses and for
generating a count value, and at least one sensor which enables the count
value to be incremented when the medical apparatus is worn, the clock
generator defining a reference time corresponding to the time required for
the clock generator to generate a predetermined number of clock pulses,
an external evaluating unit adapted for receiving the count value from the
measuring unit,
means for supplying the reference time from the measuring unit to the
evaluating unit, and
means associated with the evaluating unit for using the count value and the
reference time to calculate a length of time corresponding to the length
of time that the removable medical apparatus is worn.
2. The device according to claim 1, wherein the reference time is supplied
from the measuring unit to the evaluating unit with each receipt of the
count value by the evaluating unit.
3. The device according to claim 1, wherein the evaluating unit comprises:
means for generating a quotient substantially equal to the reference time
divided by the number of clock pulses generated by the clock generator
during the reference time, and
means for multiplying the quotient and the count value.
4. The device according to claim 1, comprising:
a bidirectional transmission channel for connecting the measuring unit and
the evaluating unit,
means associated with the evaluating unit for generating a triggering
signal and for transmitting the triggering signal to the measuring unit,
an output control unit, associated with the measuring unit and responsive
to the triggering signal, for supplying a reference time from the
measuring unit to the evaluating unit, the reference time corresponding to
a specific clock pulse number of the clock generator, and for supplying
the count value from the measuring unit to the evaluating unit in serial
form.
5. The device according to claim 1 comprising a frequency divider,
interposed between the clock generator and the counter, for generating
output pulses that are transmitted to the counter via the at least one
sensor.
6. The device according to claim 1, wherein the clock generator defines an
active state and an inactive state, and further comprising:
a sensor connected to the clock generator, the sensor defining a sensor
detection condition, and
a frequency divider interposed between the clock generator and the counter
for sending clocking pulses to the sensor, wherein the clock generator is
maintained in the active state when the sensor receives a pulse from the
frequency divider and the sensor detection condition is fulfilled.
7. The device according to claim 6, wherein the clock generator is switched
to the inactive state when the sensor receives a pulse from the frequency
divider and the sensor detection condition is not fulfilled.
8. The device according to claim 1, comprising
a first sensor responsive to moisture for activating the clock generator,
and
a second sensor responsive to temperature, the second sensor being
interposed between the clock generator and the counter, the second sensor
allowing clock pulses to pass from the clock generator to the counter when
the second sensor detects a temperature within a predetermined temperature
range.
9. The device according to claim 1, comprising:
reset means, associated with the measuring unit, for identifying a reset
signal transmitted to the measuring unit from the evaluating unit and for
resetting the counter.
10. The device according to claim 1, comprising first and second sensors
for enabling the count value to be incremented, the first and second
sensors each defining a sensor condition, the first and second sensors
being arranged so that both sensor conditions must be fulfilled in common
to enable the count value to be incremented.
Description
The invention is directed to a wearing time measuring device for a
removable medical apparatus, particularly for an orthodontic or a dental
prosthetic apparatus.
DE 28 20 358 C3 describes an orthodontic apparatus containing a measuring
unit comprising a clock generator and an electronic counter. The clock
generator and the counter are activated by a sensor detecting the presence
of the apparatus in the mouth. During the wearing times, the clock
generator delivers pulses to the counter. In this manner, the wearing
times are accumulated. By occasionally checking the counted value by an
external evaluating unit, the wearing time can be detected and displayed.
The wearing time measuring device enables the physician in charge to
control the wearing time of the apparatus in the patient's mouth so that
the physician can judge the therapeutical results with greater precision.
Also in the time measuring device for medical apparatus known from DE 32 44
695 C2, the wearing time is detected by counting the pulses of a clock
generator. Another counter is provided for counting the number of daily
applications. This known time measuring device further includes a
temperature sensor and a moisture sensor for detecting the presence of the
apparatus in the mouth and for initiating the operation of the time
measuring device.
The known wearing time measuring devices have a battery-powered measuring
means provided as a small-sized electronical unit to be fastened in
encapsulated form on the apparatus within the patient's mouth. The logic
components of such a measuring unit can be realized by integrated circuit
technology without difficulties. Also the sensors, responding to pressure,
moisture or temperature, can be provided in miniature sizes. Batteries of
sufficiently small sizes are available as well. However, the clock
generator poses difficulties in realizing a correspondingly small-sized
and encapsulated time measuring device. When clock generators or
oscillators are realized in integrated circuit technology or thick film
technology, the precision of the clock frequency will be very limited
only. The clock frequency is influenced by manufacturing parameters,
resulting in considerable manufacturing tolerances. Further, the clock
frequency is impaired by environmental and temperature influences and by
aging.
Clock generators offering high precision of the clock frequency, such as
quartz generators, are not available in the required small constructional
size. The precision of the clock measurement is directly dependent on the
accuracy of the clock generator. However, provision of a highly precise
clock generator within the miniaturized measuring unit is extremely
difficult.
It is the object of the invention to provide a wearing time measuring
device of the type indicated in the preamble of claim 1 which allows
highly accurate time measurement and wherein the measuring unit, having
the usual tolerances of constructional units, can be realized in a very
small size in integrated circuit technology.
In the wearing time measuring device of the invention, a comparatively
inaccurate clock generator, e.g. an RC oscillator, can be used. When the
counted value is transmitted from the measuring unit to the external
evaluating unit, there is transmitted also a reference time along with it,
corresponding to a predetermined number of pulses of the clock generator.
In this manner, the frequency generated by the clock generator can be
measured in the measuring unit and taken as a basis in evaluating the
value of the counter. Thus, not only manufacturing tolerances of the clock
generators are taken into consideration, but also environmental and aging
influences are included into the evaluation. This provides for highly
precise time measurement also for clock generator frequencies varying in a
wide range. It is only to be observed that the frequency of the clock
generator is largely constant during the wearing time to be measured.
Influences of temperature on the frequency of the clock generator can be
eliminated by establishing a connection of the evaluating unit to the
measuring unit immediately after taking the apparatus out of the mouth or
even while the apparatus is still kept in the mouth.
Cooperation of the measuring unit and the external evaluating unit can be
performed via leads to be connected to the measuring unit, or by wireless
operation through radio transmission.
The wearing time measuring device can be provided for measuring the wearing
time directly, or for measuring the non-wearing time, with the wearing
time calculated therefrom as a complementary value.
During read-out from the measuring unit, the counted value need not
necessarily be contained in the counter but can also be input in an
intermediate storage means. In the latter case, any desired number of
intermediate storage means can be provided, e.g. for storing the wearing
times as subdivided by days.
While the measuring unit, due to its required miniature size and the
individuality of the components, is usually arranged as a hybrid circuit
and consists of an integrated circuit portion and a thick-film circuit
portion, the evaluating unit can be a usual computer device programmed in
appropriate manner. The evaluating unit need merely carry out such
operations which can be programmed in a computer.
The measuring unit to be implanted in the mouth must have low power
requirements because the battery is suitably accommodated by being
encapsulated together with the other components of this measuring unit and
cannot be exchanged. For reducing power consumption, the invention
provides special measures wherein especially the sensors have low power
consumption and are interrogated at longer time intervals for only a short
period each time.
Preferably, a sole bidirectional channel is used for communication between
the measuring unit and the evaluating unit. This channel can be an
electric line or a wireless radio connection. Arrangement of the measuring
unit is such that the unit responds to signals of the external evaluating
unit and, upon receipt of corresponding instructions, reads out the
reference time and the counted value or resp. resets the counted value to
zero. Suitably, data transmission via the sole channel takes place in
serial fashion.
An embodiment of the invention will be explained in greater detail
hereunder with reference to the drawings.
FIG. 1 shows the arrangement of a measuring unit on an orthodontic
apparatus,
FIG. 2 is a block diagram of the measuring unit,
FIG. 3 is a block diagram of an embodiment of a external evaluating unit,
FIG. 4 is a pulse diagram of data output from a measuring unit, and
FIG. 5 is a pulse diagram during resetting of the counted value of a
measuring unit.
The orthodontic apparatus 11 shown in FIG. 1 is attached e.g. on the teeth
12 of the upper jaw 10. The orthodontic apparatus consists of at least one
molded plastic body 13 having wire clamps 14 fastened thereto for gripping
around the teeth completely or partially. It is not indispensable that the
orthodontic apparatus comprises a molded plastic body. The apparatus can
also consist exclusively of a wire structure.
The orthodontic apparatus 11 has fastened thereto the measuring unit 15
which in the present embodiment is cast into the molded plastic body 13.
Only the sensor 16, responding to moisture, is exposed on the surface of
the molded body so as to be subjected to the conditions prevailing in the
mouth.
The measuring unit 15 is encapsulated in a sealing compound together with
the battery feeding it, with only the sensor 16 being exposed.
FIG. 2 is a schematic view of the arrangement of the measuring unit 15. The
moisture-responding sensor 16 controls the clock generator 18 consisting
of an RC generator. Of the circuit of the measuring unit 15, only the
sensors 16 and 17 and the clock generator 18 are provided in thick film
technology on a ceramic substrate whereas all other components are
installed on a chip in integrated circuit technology. Sensor 16 is
arranged as a resistor bridge being dependent on moisture. Also sensor 17
is a resistor bridge, with one of its resistors being an NTC resistor.
Sensor 17 will respond if the temperature lies within predetermined
limits.
The clock pulses generated by clock generator 18 are supplied to a
frequency divider 19. The frequency divider is a binary divider which, at
its output terminal connected to sensor 17, effects a division of 2.sup.12
=4,096. This means that one among 4,096 pulses of the clock generator will
reach sensor 17. Sensor 17 allows this pulse to pass to counter 20 only if
the sensor condition is fulfilled, i.e. if the detected temperature is
within the predetermined range. Because of the comparatively low pulse
frequency, sensor 17 carries out only few switching processes so that
power consumption is low.
A second output terminal of frequency divider 19 is connected to the
moisture-responding sensor 16. At this second output terminal, a division
by the factor 2.sup.9 =512 is takes place. This means that one of 512
pulses of clock generator 18 will reach sensor 16.
Sensor 16 is arranged for being operative while detecting dryness and being
non-operative while detecting moisture. Sensor 16 activates clock
generator 18 upon transition from dryness to moisture. Thereafter, sensor
16 is switched off and will be switched on for respective short times by
the pulses of the frequency divider 19 only in order to newly activate
clock generator 18. If sensor 16 detects "dryness" when receiving a pulse
from frequency divider 19, it is switched on, thereby rendering clock
generator 18 inactive so that clock generator 18 stops oscillating. If, in
contrast, sensor 16 detects "moisture" when receiving a pulse from
frequency divider 19, it is switched off so that clock generator 18 can
continue oscillating. While the orthodontic apparatus is kept in the
mouth, sensor 16 periodically detects "moisture" and therefore does not
cause any noteworthy power consumption. Further, sensor 16 is not
permanently in a ready state for performing its monitoring function;
instead, this monitoring function is performed only during receipt of
pulses from frequency divider 19, i.e. at intervals.
The points of time when sensors 16 and 17 are interrogated by frequency
divider 19, are in no relationship to each other, i.e. both interrogations
are carried out at different times so that the sensors do not influence
each other and do not lead to increased power consumption at the same
time.
Sensor 16 has the effect that clock generator 18 is set into operation only
if moisture is detected, and sensor 17 effects that pulses of clock
generator 18 are counted by counter 20 only if the temperature lies within
the predetermined range. Thus, the conditions of sensors 16 and 17 are
conjunctively coupled, i.e. both conditions have to be fulfilled in common
for allowing a time counting to be carried out.
For reading out the counted value of counter 20 to be transmitted to the
external evaluating unit 21, the measuring unit 15 is connected to
evaluating unit 21 by a bidirectional channel 22 which can be a
single-cored line. It will be understood that in case of a wire connection
also transmission of mass potential is required.
A possible arrangement of the evaluating unit 21 is shown in FIG. 3,
irrespective of the fact that the function of this evaluating unit is
suitably taken over by a computer. The evaluating unit 21 includes a
triggering control unit 23 having a key 24 for "Read-out of counted value"
and a further key 25 for "Cancel counted value". Evaluating unit 21
further includes a receive control unit 26, a register 27 for temporary
storage of the reference time t.sub.R and a decoder 28, all of which are
connected to channel 22.
Read-out of the counted value of counter 20 into evaluating unit 21 will be
explained hereunder with reference to FIG. 4: Upon pressing key 24, the
triggering control unit 23 emits a triggering pulse AI to measuring unit
15 via channel 22. This triggering pulse, which can occur at any desired
time, is recognized by the output control unit 30 of measuring unit 15.
The output control unit 30 is connected to different output terminals of
frequency divider 19 in such a manner that the output control unit 30 can
receive every 2.sup.4 th pulse, i.e. each 16th pulse, from frequency
divider 19. In the present case, the reference time t.sub.R is the time
elapsing while clock generator 18 generates a predetermined number of
pulses (16 pulses). By the triggering pulse AI, clock generator 18 is put
into operation, and output control unit 30 emits to channel 22 the pulses
supplied to unit 30 from frequency divider 19, the numbers of said pulses
being indicated in FIG. 4 along the abscissa. The 1st pulse is the start
bit SB, which is outputted when after the triggering pulse AI, a bit is
delivered from the frequency divider 19 to the output control unit 30 for
the first time. The subsequent reference time t.sub.R extends from the
beginning of the 1st bit to the beginning of the 17th bit. Thereafter,
transmission of the 16 data bits DB forming the contents of counter 20 is
carried out. To this purpose, the value of counter 20 is applied to
channel 22 via a parallel-to-serial converter 31. In the evaluating unit
21, the receive control unit 26 provides that the data bits DB are
supplied to the decoder 28.
The reference time t.sub.R measured by the time measuring means 27 is
divided in the divider 32 by the number n=16 of the pulses of the clock
generator forming the reference time whereby the cycle length of a clock
pulse is detected. In the multiplier 33, the pulse number obtained in
decoder 28 is multiplied by the cycle length of a pulse, and the result is
displayed as the wearing time in display means 34.
FIG. 5 shows the case that the key 25 on the evaluating unit 21 has been
pushed for transmitting a reset instruction for resetting the counted
value to measuring unit 15. Also in this case, there is first outputted a
triggering pulse AI from evaluating unit 21. In reaction to this
triggering pulse, the output control unit 30 outputs the 1st pulse as the
start bit SB. This start bit is received by evaluating unit 21 which
thereupon emits a reset pulse LI after a predetermined time prior to lapse
of the reference time t.sub.R. This reset pulse LI, whose length is larger
than that of the pulses of the clock generator, in this example coincides
with the bit No. 3 of the clock generator. The reset means 35 of the
measuring unit recognizes the simultaneous occurrence of reset pulse LI
and Bit No. 3 and thereupon initiates the resetting of the counted value
of counter 20. Thereby, counter 20 is reset to the count "zero" so that a
new wearing time can be measured.
The measuring unit can additionally include a storage means for an
identification number which together with the other data is supplied to
the evaluating unit so that the measured values can be stored along with
the identification number of the respective apparatus in the evaluating
unit.
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